Make IO a static class instead of a singleton.

test/closure/assign_to_closure.wren

@@ -4,15 +4,15 @@ var g = null
 {
   var local = "local"
   f = fn {
-    io.write(local)
+    IO.write(local)
     local = "after f"
-    io.write(local)
+    IO.write(local)
   }
 
   g = fn {
-    io.write(local)
+    IO.write(local)
     local = "after g"
-    io.write(local)
+    IO.write(local)
   }
 }
 

test/closure/close_over_function_parameter.wren

@@ -2,7 +2,7 @@ var f = null
 
 fn(param) {
   f = fn {
-    io.write(param)
+    IO.write(param)
   }
 }.call("param")
 

test/closure/close_over_method_parameter.wren

@@ -3,7 +3,7 @@ var f = null
 class Foo {
   method(param) {
     f = fn {
-      io.write(param)
+      IO.write(param)
     }
   }
 }

test/closure/closed_closure_in_function.wren

@@ -3,7 +3,7 @@ var f = null
 {
   var local = "local"
   f = fn {
-    io.write(local)
+    IO.write(local)
   }
 }
 

test/closure/closed_closure_in_method.wren

@@ -4,7 +4,7 @@ var foo = null
   var local = "local"
   class Foo {
     method {
-      io.write(local)
+      IO.write(local)
     }
   }
 

test/closure/nested_closure.wren

@@ -7,9 +7,9 @@ fn {
     fn {
       var c = "c"
       f = fn {
-        io.write(a)
-        io.write(b)
-        io.write(c)
+        IO.write(a)
+        IO.write(b)
+        IO.write(c)
       }
     }.call
   }.call

test/closure/open_closure_in_function.wren

@@ -1,6 +1,6 @@
 {
   var local = "local"
   fn {
-    io.write(local) // expect: local
+    IO.write(local) // expect: local
   }.call
 }

test/closure/open_closure_in_method.wren

@@ -2,7 +2,7 @@
   var local = "local"
   class Foo {
     method {
-      io.write(local)
+      IO.write(local)
     }
   }
 

test/closure/reference_closure_multiple_times.wren

@@ -3,8 +3,8 @@ var f = null
 {
   var a = "a"
   f = fn {
-    io.write(a)
-    io.write(a)
+    IO.write(a)
+    IO.write(a)
   }
 }
 

test/closure/reuse_closure_slot.wren

@@ -3,7 +3,7 @@
 
   {
     var a = "a"
-    f = fn io.write(a)
+    f = fn IO.write(a)
   }
 
   {

test/closure/use_global_in_function.wren

@@ -2,5 +2,5 @@ var global = "global"
 // TODO: Forward reference to global declared after use.
 
 fn {
-  io.write(global) // expect: global
+  IO.write(global) // expect: global
 }.call

test/closure/use_global_in_method.wren

@@ -3,11 +3,11 @@ var global = "global"
 
 class Foo {
   method {
-    io.write(global)
+    IO.write(global)
   }
 
   static classMethod {
-    io.write(global)
+    IO.write(global)
   }
 }